基于滑动质心法的华南地区锋面和暖区降水ECMWF模式预报性能评估

Evaluation of ECMWF model forecasting performance for front and warm-area rainfall in South China based on the sliding centroid method

应用空间滑动质心法对2018—2020年华南地区锋面和暖区中雨、大雨及暴雨量级降水ECMWF模式(简称EC模式)24~168 h时效的空间落区预报结果进行定量分析。结果表明:EC模式对华南暖区降水和锋面暴雨的空间落区预报存在系统性经纬向偏差,且以偏西北为主;对锋面中雨和大雨的空间落区预报存在系统性经向偏差,且以偏北为主,但纬向偏差不明显。模式对锋面和暖区降水空间落区预报的纬度偏差分别集中在1.0°和1.5°以内,经度偏差分别集中在1.5°和2.0°以内。随预报时效增加,EC模式的空间预报偏差增大,24~72 h时效的EC模式空间落区预报相对稳定,96~168 h时效的预报偏差明显增大。2022年华南地区两次锋面和暖区降水空间位置质心订正结果表明,订正后的模式降水TS评分明显提高。

Based on the sliding centroid method,the spatial rainfall location forecast performance of EC model in 24~168 h for moderate,heavy,and torrential rainfall in the front and warm areas of South China was analyzed.The results show that the ECMWF model(abbreviated as EC model)has systematical meridional and zonal deviation in warm-area rainfall and front rainstorm location,and the forecasted rainfall location is located west and north to the observed one.The location deviation of front moderate rain and heavy rain is dominantly meridional ones,in which cases with north rainfall deviation are more than the south one.The zonal displacement error is not clear.The meridional deviation of front and warm-area rainfall location lies in 1.0°and 1.5°,respectively.The zonal deviation lies in 1.5°and 2.0°,respectively.The spatial rainfall location forecast performance of EC model is different with the different valid time,which is relatively stable in 24~72 h.The forecast deviation in 96~168 h increases obviously.A method for correcting the spatial rainfall location is established.The deviation correction method is applied to two rainfall events in 2022,and the results show that the TS scores can be significantly improved.